This invention relates broadly to a preassembled nut and workpiece system, and more particularly to a clamping joint assembly designed to secure one workpiece to a fragile workpiece.
With the increasing use of plastic and plastic-like filled material to replace steel and other steel metal materials, the problem of reducing the compressive stress on one or more work panels being fastened together becomes more important.
A series of structural plastic materials, which may broadly be described as including some sort of fill in the thermo-plastic structure, creates special problems in that they are unusually susceptible to fracture or otherwise deteriorate when placed under clamping stress. This failure in the plastic-like panel can also be accelerated when the panel is under stress and then the joint is also subjected to environmental changes such as moisture, heat, cold, etc.
The purpose of this invention is to provide a nut member and a joint which includes a particularly designed nut member which relieves and isolates compressive stress from the critical frangible panels.
It is, thus, an object of the invention to provide a fastener member, namely a nut device which is capable of being associated with a fragile panel and that can thereafter be utilized with a male threaded fastener member to compressingly attach a second work panel to the first fragile member without creating stresses on the fragile panel which would tend to fracture or otherwise fail.
These objects are accomplished by a tubular nut member which has a tubular section of a predetermined length and further includes a radially extending flange from adjacent one extremity of the tube. The flange is configured so that its innermost periphery is spaced slightly both in a radial direction and the axial direction downwardly from the extremity of the tube. The flange is planar and is oriented to lie in a plane generally perpendicular to the axis of the tube with one surface of the flange being coated or provided with a layer of adhesive material. A further aspect of the invention is the dimensional relationship between the apertures in the panel to be attached and the aperture in the fragile panel. The preformed hole in the panel to be attached should be slightly smaller than the preformed hole in the fragile panel to permit the extremity of the tubular section to abut against the other panel as it is resiliently compressed during application based upon the hinge or rim that separates or spaces the flange from the extremity. The combination of the spring take-up and isolation of the compression by virtue of the columnar effect of the tube in addition to the secondary compression isolation resulting from the layer of adhesive completely eliminates stress at the region surrounding the hole in the fragile panel.